My current home setup is the following:
dsl modem transmits signal to a linksys 802.11g router which in turn sends the signal through either wired ethernet or to several laptops through a wireless connection, so like the following:

how do i make it so that the laptop in a completely different room without access to a phone jack be able to have access to an ethernet line without hardwiring my house from the router all the way to where the laptop is? so like the following:

The way you are describing is probably possible but not without some uncommon (read: expensive) equipment.

The easiest way to get her laptop back online would be to buy another wireless interface as they're much, much, much cheaper than any of the alternatives and more robust than Ethernet over Power (which has problems with data rates and doesn't work at all if parts of your house have isolators).

You can get her either a USB adaptor or PCMCIA card. They're about £20 in the UK for a cheap one.

billybob

I managed to get a USB WI-FI adapter from good old eBay for £14 including postage and its working fine for me, it has to be the easiest solution to your problem.
Ryan

Bones

Either buy a new wireless card, tell your sister to move into the room with the router, or buy a whole lotta ethernet cable.

rfwrangler

There are a lot of wireless adapters that are available that are wireless to ethernet adapters. You can get these relatively inexpensively or you can spend a lot of money. What determines the price are the feature sets that you need and the reliability that you are looking for.

If you are looking to set up ad-hoc networks then you will need a more expensive version. There are a lot of factors that you will want to look at and I would be happy to help you in any way that I can.

jefry66

use ethernet over power
you can buy it in a computer shop

jwellsy

If you find a wireless card for your pc you might be able to move the modem/router into the other room.

turbosquid

If your sisters WIFI card is not working you may be able to buy another one, but i would imagine that it may be expensive unless you can get one of eBay second hand for cheap.
Another option if your sisters laptop has USB would be to get a USB to WIFI adapter they are plentiful and cheap to you can get them from most computer shops and even cheaper online.

If your sisters laptop dosent have USB then you coud use an Ethernet to WIFI bridge. A bridge is basicaly a device that connects two networks using either the same or different protocols. They are commonly used for connecting games consoles such as an XBOX with a normal Ethernet port to a wireless lan.